Scleroderma (sklair-oh-DUR-muh), also known as systemic sclerosis, is a group of rare diseases that involve the hardening and tightening of the skin. It may also cause problems in the blood vessels, internal organs and digestive tract. Scleroderma is often categorized as "limited" or "diffuse," which refers only to the degree of skin involvement. Both types can involve any of the other vascular or organ problems. Localized scleroderma, also known as morphea, affects only the skin.